Field of the Invention
The present invention relates to an endoscope system and a signal processing apparatus and relates to an endoscope system including an endoscope including a solid-state image pickup device driven by a predetermined clock signal, and a signal processing apparatus connected to the endoscope.
Description of the Related Art
Endoscope systems each including, e.g., an endoscope configured to pick up an image of an object inside a subject and an image processing apparatus (signal processing apparatus) configured to generate an observation image of the object picked up by the endoscope have widely been used in a medical field, an industrial field, and the like.
As the endoscope in such an endoscope system above, an endoscope employing a solid-state image pickup device (for example, a CMOS image sensor) driven by a predetermined clock signal and including a cable disposed inside, the cable being configured to transmit an image pickup signal outputted from the solid-state image pickup device, has conventionally been known.
In general, this type of endoscope includes an image pickup device such as above in a distal end portion of an insertion portion. Also, as for clocks supplied to the image pickup device, for example, clocks are supplied to the image pickup device from an external signal processing apparatus via a cable inside the endoscope.
Here, as for the supply of clocks from the signal processing apparatus to the image pickup device, an example in which clocks are transmitted by means of what is called differential signals, via the cable has been known. Inside the cable, power supply channels of various types of power supply from the signal processing apparatus to the image pickup device (for example, a digital power supply channel VCCDIG, an analog power supply channel VCCANA and an I/O power supply channel VCCIO) are provided (see FIGS. 10 and 11).
Furthermore, in recent years, an example in which as an image pickup device in an endoscope, a CMOS (complementary metal-oxide semiconductor) image sensor is employed has been proposed (Japanese Patent Application Laid-Open Publication No. 2006-095330).
In an endoscope system 901, which is illustrated in FIG. 10, an overcurrent sensing circuit 68 is provided on the signal processing apparatus 903 side, which is connected to an endoscope 902, to detect a shorted state in a power supply channel.
Also, an endoscope system 911, which is illustrated in FIG. 11, has a configuration in which sensing circuits (detection sections) 69a, 69b are provided in respective clock signal transmission channels on the signal processing apparatus 913 side, which is connected to an endoscope 912.